Question

Difficulty: MediumBiomes and Aquatic/Terrestrial Habitats

Plants inhabiting estuarine and mangrove swamp biomes face severe physiological stress due to waterlogged, oxygen-deficient muddy substrates and fluctuating salinity. Which of the following specialized adaptations enables mangrove plants (such as Rhizophora and Avicennia) to survive in this habitat?

  1. Development of erect, negatively geotropic breathing roots (pneumatophores) bearing lenticels for atmospheric gaseous exchangeAnswer
  2. B
    Modifications of xylem vessels to translocate manufactured organic food bidirectionally from aerial leaves to subterranean roots
  3. C
    Complete absence of internal vascular tissues, forcing reliance on direct cell-to-cell diffusion for water absorption across aerial leaves
  4. D
    Presence of feathery, exposed stigmas and light, smooth pollen grains specifically adapted for underwater wind pollination

Answer

Development of erect, negatively geotropic breathing roots (pneumatophores) bearing lenticels for atmospheric gaseous exchange
Mangrove biomes feature waterlogged, anoxic mud. To overcome oxygen deficiency around the root system, plants develop negatively geotropic breathing roots (pneumatophores) equipped with lenticels that absorb atmospheric oxygen.

Step-by-Step Solution

1
Identify the key abiotic stresses of estuarine and mangrove swamp biomes.
The substrate is poorly aerated (anoxic), waterlogged, and experiences high salinity levels.
Estuarine mud lacks free oxygen gas essential for aerobic respiration in submerged root tissues.
2
Evaluate anatomical adaptations of mangrove vegetation against these abiotic stresses.
Negatively geotropic roots (pneumatophores) project upward out of the mud into the air, utilizing lenticels to intake oxygen.
Direct atmospheric gaseous exchange bypasses the oxygen-depleted substrate.

Key Concept

Adaptive structural features of organisms in mangrove/estuarine biomes
Estimated Time:1m 0s
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